pregnancy

so on the 25th i was suppose to start my period, on the 27th i figured i should take a test so i did and there were 2 lines one super strong and the other kind of faint. so i went to the store and bought more and the same thing happened it came up positive. the next day (the 28th) i took one and same thing, positive. then the 29th i started bleeding but not a lot, and took a test and all of a sudden negative. took another one and negative again. and still bleeding so i’m guessing it’s my period but i’m so confused as to why i would get three positive pregnancy tests and then suddenly get my period? i talked to doctors and they do not think it is a miscarriage either. help.